To (someday) finalize my Librem 5 order I need some helping making a modem choice (i.e. band and frequency support) and a network choice (i.e. a cellular plan).
I’m not a network engineer and I’m not a cell phone expert either.
I live in rural California (USA) where Verizon has the best cellular coverage, followed by AT&T and T-Mobile, in that order.
I’m getting bogged down in all of the Jargon and various mode and band names.
I’m guessing what I’m shooting for is good LTE (“mode”) support hopefully with V0LTE over it. (BTW, is “mode” now called “interface” in modern parlance?) Also, I think there should be GSM and PCS support for fallback mode for voice?
As near as I can tell the BroadMobi BM818-A1 is the best modem for both Verizon, AT&T, and T-Mobile, but I’m not yet 100% sure???
What I think is true is that LTE superseeds both Verizon’s use of CDMA and AT&T’s use of GSM and EGSM, and has pretty good cell tower support by now.
http://niviuk.free.fr/lte_band.php helps narrow bands down a bit with the region of “NAR” (the North America Region) using LTE bands:
2, 4, 5, 10, 12, 13, 14, 17. 23, 24, 25, 26, 27, 29, 30, 66, 70, 71, 74, 75, 76, and 85. But this is not of too much help.
https://puri.sm/faq/supported-networks/ lists the 4 available Librem 5 modems: Gemalto PLS8-E & PLS8-US, and BroadMobi BM818-E1, & BM818-A1, and shows which modems support which GSM, HSPA and LTE bands.
For fallback mode (falling back from LTE), all four modems seem to support either:
- GSM (the old European/global standard) or
- EGSM (the newer GSM)
- PCS (the old basic Personal Communications Service) or
- DCS (Digital Cellular System, which I’m not really sure what this is).
Is this correct for fallback modes?
Also looking at the BroadMobi BM818-E1 it seems to be the modem which supports all needed LTE-FDD (Long Term Evolution - Frequency Division Duplex) bands for Verizon, At&T and T-Mobile, except B14, B29, B30, and B71:
Verizon: B2, B4, B5, B66, … B13,
AT&T: B2, B4, B5, B66, … B12, B14, B17, B29, B30
T-Mobile: B2, B4, B5, B66, … B12, B71
Near as I can tell
B14 is used only for emergency services
B29 is used for supplemental downlink
B30 is used for additional capacity (?? as an alternate channel??), and
B71 is an optional band, as it’s not yet used by many phones.
So none of these are critical.
Am I on the right path?
…Next is to figure out how to order ANY cellular plan from any any of these companies, as none of them list the Librem 5 as supported, or even acknowledge it’s existence. Any thoughts on this?